Production of water-soluble titanium compounds



Patented Nov. 21, 1939 r COMPOUND raonuo'non F WATER-SOLUBLE TITA- mum s Edward N. Kramer, Wilmington, DeL, asslgnor to E. I. do lo ntde Nemours & Company, Wilmlngton, Del., 2 corporatlonol' Delaware Serial No. 233,747

Ne Drawing. Application October 7,1938,

c'fci ims. (oi. -115) I inventionrelates to the production of water-soluble titanium compounds through acid attack of titaniferous ores; and particularly to the recovery of soluble titanium values from that part of .the ore which remains insoluble after initial acid attack. More specifically, the'invention concerns the recovery .of titanium values from titanium-containing residues obtained from the suli'uriefacid attack of ilme'nite.

Previously, various processes for the production of titanium solutions "from' titanium ores such as ilmenite have been proposed: One useful process includes that disclosed in U. S. Patent 2,112,966; Others include those described in U. S. Patents 1 014393 011.1,889,027,the latter being especially useful when finely-ground ore and strong sulfuric acid are employed in the attack. In such processea'asjolution isiproduced which contains finely-divided-mud's and slime, which can only :be precipitated and recovered by colloidal processes requiring use of certain coagulants such as heavy metal sulfides or-glue. A conveniently useful clarification process com prises that described in-U. ;S Patent 2,111,788,-

wherein such muds are coagulated by addition .of sulfides or glue, settled toia thick'consistency, after which they are withdrawnfromtahks sucli as the well-known Dorr thi'ckenera in relatively concentrated mud suspension, This suspension is usually washed, further-settled to reeover the titanium values which appear in the solution, and the mud, which constitutes a serious disposal problem, after dewaterin'g, is" discarded. Al-

though, in U. 8; Patent 2,093,026 it has been proposed to eflfect solubili'zation of the titanium values in such solid muds, such process has not proven completely and desirably successful and satisfactory because an undesirably low yield of soluble titanium oxide has been found to result, and in addition, the uhattaeked residue remaining is of such quantity aa-tenot desirably overcome the disposal problem "which the dis- "card of such muds presents.

It is among the objects of my invention to overcome these and other disadvantages in prior processesfand to provide an improved process for the utilization'of previously discarded residues in titanium-oxide pigment producing operations, and one which'is inherently adapted to erect relatively complete solubilization and recovery of the titanium values inTsuch residues. A further and particular object includes the pro-.

slimes and muds has presented to the titanium industry. A special object of the invention is to provide a process for the complete solubilization of titanium oxide present in the colloidal residues now settled from titanium salt solutions, and especially solutions of titaniumsulfate. A

further object is to provide a process for the recovery of acid which is entrained in such residues and to usefully employ the same in partial" substitution of the acid which is required during ore attack. A further object is to provide a simple and economical method for recovering the soluble titanium entrained with said residues 7 without requiring resort to special, costly and prolonged washing and filtering operations.

These and other objedts and advantages are accomplished in this invention-which comprises returning the titanium-containing residues produced in a previous ore attack and clarification operation to the acid attack portion of the process,.and so treating said residues as to cheat their solubilization and render the same useful in solubilizlng titanium ore subjected to acid attack. In a more specific and preferred embodiment, the invention comprises solubilizing a titaniumcontaining residue; such as a mud or slimefrom a clarification underfiow of a process for producing titanium values, by treating such residue with relatively strong sulfuric acid (in excess of about vision oft-a process adapted to effectively overcome and ifiiiaimize toa negligible extent the residue W disposal problem which the production of residual strength) and in amount substantially greater than that theoretically necessary to produce the sulfates 'of the metallic materials present in said residue, and then. utilizing the resultant mixture in the acid attack of a fresh charge. of titaniferous ore. In one preferred adaptation of the invention,

wherein a titanium sulfate solution is produced as a result of a batch attack on ilmenite ore by sulfuric acid, the residual muds settled .out as the underflow in the clarification portion of such system are conveniently recycled to the acid-ore attack portion of said process and mixed with strong sulfuric acid at a strength in excess of 85%, such as oleum, or'66 B. or higher acid. The amount of acid thus employed is preferably not less than about twice that theoretically necessary to efiect complete sulfation of the titanium and iron present in said residue or slime, and to produce a mixture having in excess of 80%, H2804 strength. Usually, such mixtures are employed as will yield an acid mix of approximately 96% strength at a temperature substantially in excess of 0., whereby the acid/T10: ratio obtained becomes many times -30 wise in limitation of the invention:

greater than that normally employed in ilmenite 1 ore. attack. Strong agitation is resorted to during mixing and much heat is evolved. As the strength of the acid increases during mixing, the titanium oxide present in the mud reacts therewith to form soluble titanium sulfate. Upon completion of mixing and conversion of the titanium to soluble state, the acid strength is suitably adjusted by addition of dilute, recovered hydrolysis acid, and the temperature of the mixture increased by injection of steam. The mixture may be then employed in the main attack by \directly adding the same to acid to be utilized in such attack or to mixtures of acid and fresh ore 5 undergoing attack.

As a resultof this simple procedure of initially contacting residual muds or slimes with strong sulfuric acid prior to their use in or addition to the regular titaniferous ore attack, a substan- 20 tial and desired increase in yield of titanium oxide will be found to result. Thus, whereas a yield of about 90% has been obtainable heretofore, adoption of the instant process will be found to effect a yieldranging to as high as 96-98% of TiOz. In addition; the previous residue disposal problem will be found to be no longer confronting.

In order that the invention may be more clearly understood, the following illustrative example is given, which is not to be considered as a Example I L and 2000 pounds of oleum were-added while the Y pan was agitated. The mixture became quite hot and reaction between the mud and strong acid took place. The acid strength was suitably adjusted by addition of recovered hydrolysis acid running 25% in strength, and the temperature raised by steam injection to 215 C., during which time substantially complete conversion of the TiO: present in the mud to the sulfate was accomplished. The coarse sand ilmenite was next added over a period of 12 minutes, during which time 1700 pounds of such ore were added. At the end of the addition a solid mass was obtained which was stored for 12 hours and later dissolved.

As indicated, although specific procedures for effecting mixtures of the residual mud or slime with sulfuric acid have been resorted to in the foregoing example, the acid may be mixed with the mud-containing cake or suspension, either before or after dewatering, such as in a filter press, thereby producing a solid mud which may be conveniently repulped in sulfuric acid with the aid of strong agitation. Alternatively, the thickened underfiow from the clarification tank may be. pumped to a tank where it is mixed with the strong sulfuric acid, using suflicient acid to build up 'the suspension to a concentration in excess of 85% msoi in the mixture. In the event the thickened mud suspension is removed from the clarification tank and reacted without further treatment, the same may be pumped directlyfrom the tank to a mixing vessel where mixing with 75 the sulfuric acid occurs; This tank must be able to withstand acid and high temperatures, due to the fact that heat is generated-by virtue of the dilution of the acid as it is mixed' with the mud suspension. While the mud suspension may be added to the acid, I prefer to carry out the reaction in the opposite manner, i.'e., add the acid to the titanium suspension, although if desired simultaneous addition of the two to a reaction vessel may beresorted to.

Also, th acid-mud mixture may be added to the main body of the attack in other ways. Thus, the sulfated mud-acid mixture may be added to the acid either before or after the ilmenite has been added to 'such acid. In the event coarse ilmenite isemployed, it will be found preferable to add'the sulfated mud mixture to the acid prior to the addition of the ilmenite. In instances where attacks are being made with finely-ground ilmenite, it will be found preferable sometimes to add the mud-acid suspension to the acid prior to addition of ilmenite, although such operation is not to be recommended in the event the mud contains a large percentage of titanium values going to the attack. In such procedures, at least of the titanium should be coming from the ilmenite, otherwise too much heat will be added to the attack vessel prior to the slurry of the ilmenite in the acid. To avoid premature attacks during mixing, a safer procedure will be found to slurry the ilmenite in fresh acid and subsequently mix the ilmenite-acid mixture with a sulfated mud-acid mixture just previous to initiation of the attack.

As indicated, I find that reaction between the mud and acid does not desirably take place except in the presence of relatively strong sulfuric acid, that is, acid in excess of strength, and

'whn such acid is present in excess amounts.

Preferably, I employ 66 B. (93.9%) or higher strength acids, 20% (104.5% strength) being especially beneficial and useful in the invention. Likewise, 98% acid from contact acid-producing plants may also be employed, if available. The resulting acid-mud mixture is of very little use for the recovery of ti-' to convert the titanium values of the solid to the soluble state under conditions of high acidity and high strength acid. The mixture may then be subsequently employed in ilmenite attack by continuing the attack through the addition of ilmenite to the pan under the conditions set forth in said patent. Under such circumstances, all of the fuming, or oleum acid 40 necessary conditions already alluded to will be maintained.

In the event ground ilmenite, of such fineness that, to a large extent, it-passes through a 200- mesh screen, is used as a source for titanium,'it will be found desirable to first mix the strong acid and the mud so that the resultant mixture reaches at least 85% acid strength, and then add such mixture to an attack vessel in which is placed a suspension of ilmenite in cold acid.

The mixing of these unlike suspensions causes the attack to proceed and, as a result, an attack mass will be produced in which substantially complete conversion of the titanium oxide in the mud to titanium sulfate is effected.

In another variation of the invention, the mud suspension may be conveniently mixed with strong sulfuric acid, causing the two to react under strongly acid conditions, as indicated, and subsequently this reaction mixture may be added to cold acid in a large attack vessel and ground ilmenite added to the acid-mud mixture, the reaction being set off by the subsequent injection of steam or the addition of water which will effect the desired increase in temperature to initiate such reaction. Also, if desired, after addition of the strong sulfuric acid to the mud 5 and its attack by a short digestion, a 60 B. acid may be then added to the mixture followed by relatively fast addition of fresh ore and the attack set off in the usual manner through injec-' tion of steam or addition of water.

13 As will be noted in the foregoing operations, the colloidal muds are recirculated and returned to the attack with sulfuric acid. Should such muds contain siliceous materials such as are present in various ilmenite ores, the silica-bearing material will build up in the system unless there is a purging of the muds from the system. In such instances, it will be found convenient not to return more than about 80% of the muds, due to this increase in the amount of silica being recycled through the system. Should purer ilmenites be employed, such as those which are freer of silica, this recirculation may be increased to an amount up to or in excess of 90%, although generally I do not perfer to utilize 100% recirculation.

As indicated, it is possible through my novel process to increase the yield of titanium oxide from titaniferous ores from about-90% up to 96-98% by the simple procedure of contacting 40 residual muds or slimes with strong sulfuric acid prior to their addition to the regularore attack:

I am aware that it has been previously proposed to add residual muds to the regular attack, but none of such prior procedures contemplate the utilization of stronger acids nor the increase in yields or elimination of residue disposal problems which I effect. Furthermore, the present invention constitutes a much simpler operation and does not require the use of highly expensive 5o equipment, thereby rendering my process much more economical and commercially attractive. Also, the present process affords a very flexible operation, since by it one is enabled to continue more or less the same operation, either with or without the presence of the muds. Consequently, one is free to operate employing recycled slimes a portion of the time and practice the prior art straight titaniferous ore attacks the remaining times.

I claim as my invention:

1 A process for producing solubilized titanium containingproduct from the clarification stage of a titanium oxide producing operation to treatment with sulfuric acid at such strength as to substantially completely convert the titanium content of said residue to sulfated condition, and utilizing the resultant acid-titanium sulfate mixture in effecting solubilization of a titaniferous ore through acid attack.

2. A process for producing solubilized titanium values, comprising subjecting a residual titaniumcontaining product from the clarification portion of a titanium oxide producing system to treatment with sulfuric acid of at least strength and in amount substantially at least twice that theoretically required to completely convert the titanium content of said residue to sulfated condition, and utilizing the resultant acid-titanium sulfate mixture in effecting solubilization of a titaniferous ore through acid attack.

3. A process for producing solubilized'titanium values, comprising subjecting a titanium-com taining mudfrom the clarification stage'of a titanium pigment producing operation to treatment with sulfuric acid of at least-85% strength and in amount equalling at least twice that theoretically required to convert the titanium and,

iron present in said mud to sulfated condition, and utilizing-the sulfated titanium-iron acid mixture thus'obtained'as a component part ofkthe initial attack in a reactionbetween ilmenite and sulfuric acid.

4. In a process for producing titanium solutions from titaniferous ores, the stepsof mixing the recovered titanium-containing slimes from previously prepared'titaniurn solutions with strong sulfuric acid ,of at least 85% strength, whereby complete conversion and solubilization of, the titanium values-in said'slimes is'efljected, and

thereafter employing the resultant mixture as a decomposition agent for the sulfation of said titanifero'us ores.

5. In a process for the preparation of titanium solutions from titanium ores, the steps of mixingthe recovered titanium containingslimes from previously prepared titanium solutions with sulfuric acid having a strength in excess of about 85%, whereby complete conversion and solubilization of the titanium values in said slimes is effected, and thereafter using the resultant mixture as a decomposition agent for the sulfation of titanium ores.

6. In a process for the preparation of titanium solutions from titanium ores, the steps ofl'mixing the recovered titanium-containing slimes from previously prepared titanium solutions with sulfuric acid having a strength in excess of about 85% and in amount of not lessthan twice that theoretically necessary to completely sulfate the titanium content of said slimes, and thereafter employing the resultant mixture as a decomposition agentior the sulfation ofv titanium ores.

' EDWARD N. KRAMER. 

